in src/lib/sortedList.js [167:180]
SortedList.prototype.unique = function(createNew) {
if (createNew) return this.filter(function(v, k) {
return k == 0 || this._compare(this[k-1], v) != 0;
}, this);
var total = 0;
this.map(function(v, k) {
if (k == 0 || this._compare(this[k-1], v) != 0) return null;
return k - (total++);
}, this)
.forEach(function(k) {
if (k != null) this.remove(k);
}, this);
return this;
};